Dvorak International

This extension adds the Dvorak International keyboard layout to Chrome OS devices. It's a straightforward upload of the dvorak-intl directory from https://github.com/google/extra-keyboards-for-chrome-os, which is provided by Google under the Apache License. The only change that I've made was to remove comments from the manifest.json file since the Chrome Web Store doesn't seem to accept them. The icon is from https://materialui.co/icon/keyboard.